Copper compounds of mercaptans derived from pinene



Patented Sept. 10, 1946 COPPER COMPOUNDS OF MERCAPTAN S DERIVED FROM PINEN E Arthur L. Fox, Woodstown, N. J., assignor to E. I. du Pont de Ncmours & Company, Wilmington, Dcl., a corporation of Delaware No Drawing. Application April 23, 1942, Serial No. 440,255

This invention relates to new and valuable copper compounds and more particularly to the copper compounds of mercaptans derived from pinene.

It has recently been found that the addition of certain copper containing compounds to lubricating oils used in internal combustion engines imparts thereto desirable properties more particu larly with regard to the stability of the oil. The copper containing ionogenic compounds which have been previously suggested for use in lubricating oils have certain disadvantages in that they do not effectively inhibit and often tend to 7 cause bearing corrosion where the usual types of alloy bearings are employed in the engines. These copper containing compounds have also been found to have strong tinctorial properties and impart to the oils unnatural colors in the green, blue and purple range which are undesirable.

It is an object of this invention to produce new sulfur and copper containing non-ionogenic organic compound from the relatively inexpensive and readily available unsymmetrical bycyclic terpehes which shows excellent solubility in organic compounds and lubricating oils and which impart to lubricating oils valuable non-sludging,

. non-lacquering and non-corrosiv properties and which will not give to such .oils unnatural and undesirable colors. It is a further object of the invention to provide new and valuable lubricating oil treating compounds comprising the copper salts of mercaptans derived from pinene.

I have found that the copper mercaptides derived from pinene, which may be prepared .by reacting upon mercaptans derived from pinene with copper or copper salts, show excellent solubility in lubricating oils and because of their high copper content are particularly useful in decreasing the sludge formation and lacquering properties of the oil and in decreasing bearing corrosion in those cases where the oils tend to corrode alloy bearings. These copper compounds of mercaptans derived from pinene, furthermore, do not have the strong tinctorial properties of the previously suggested compounds but instead color organic solvents and oils when dissolved therein in light yellowto red and brown shades, depending upon their purity, which are not objectionable. These new copper and sulfur containing compounds are made directly from pinene, which is an inexpensive and readily available intermediate, by a imple and economical process.

The compounds of the present invention may be prepared by reacting pinene with sulfur at temperatures of from 75 to 200 0., treating the 1 4 Claims. (01. 260-438) resulting pinene-sulfur complex with hydrogen in the presence of a hydrogenation catalyst that is active in the presence of sulfur, to form the mercaptan, reacting the mercaptan derived from pinene with a copper salt, preferably under conditions which maintain the copper salt in a cuprous state, and isolating the copper mercaptide or extracting it from the reaction mass with a olvent such as organic solvents or lubricating oil. The sulfurization and hydrogenation may be carried out simultaneously in the presence or in the absence of an organic solvent. The formation of the copper compound may be effected directly in the organic solvent solution of the mercaptan or after isolation of the mercaptan, all as more particularly described in copending application Ser. No. 440,253, filed of even date herewith. A mercaptan derived from pinene may also be formed from pinene by the addition of hydrogen sulfid in the presence of sulfuric acid, phosphoric acid or other catalyst as more particularly described in U. S. P. 2,076,875. The

'mercaptans may be reacted with the copper salt cuprous acetate in which there has been dissolved a reducing agent such as sodium hydrosulfite. This particular reducing agent not only maintains the copper in the cuprous state but it also tends to reduce any disulfide that might be formed in the reaction to the mercaptan whereby the yield of the copper mercaptid derived from the pinene is materially increased.

Because these new copper mercaptides derived from pinenesare so exceedingly soluble in solvents and oils they may be dissolved directly in lubricating oil by stirring with or without heatingor they maybe dissolved in anorganic solvent or in lubricating oil in high concentrations to be used as a stock solution in treating lubricating oils. The copper mercaptides derived from pinene are soluble in mineral oils, and hydrocarbon solvents such as benzene, hexane, paraffin oil, etc., as well as in organic solvents such as ether, alcohol, dioxan, etc.

The following exampl are given to illustrate the invention. The parts used are by weight.

Example 1 1756 parts of alpha-pinene (having a distilling range of 156.2 C. to 157.7 C. with 90% distilling between 156.3" C. and 157.0 C. a refractive index of N20 1.4652 and a specific gravity of 0.8638) and 400 parts of sulfur are heated in an autoclave at 150 C. for 8 hours under autogenous pressure. The reaction mixture is cooled to room temperature and 75 parts of nickel catalyst are added. The mixture is then hydrogenated at 150 C. and 600-700 lbs. per sq. in. Thisreaction requires from 8 to 9 hours. The mixture is heated at 150 C. for one to two hours after the last pressure drop to ensure complete reaction. After cooling to room temperature, the catalyst is removed by filtration, and the crude mercaptan derived from the alpha pinene is fractionally distilled at 25 mm. pressure, giving an essentially pure mercaptan having a boiling range of 114.5-114.6 C., a refractive index of N26 1.5024 and a sulfur content of 18.87%. This distilled material on cooling to -5 C. for 24 hours, yields large, white crystals melting at 55.0 C. and a liquid fraction. After esterifioation with acetyl chloride in pyridine, th compound absorbs two atoms of iodine per molecule. Both the crystalline mercaptan and the liquid fraction show strong absorption bands at wave lengths of 14.00; 12.65; 11.55; 11.30; 11.0; 10.65; 10.45; 10.15; 9.90; 9.60; 9.30; 9.10; 8.90; 8.75; 8.40; 8.20; 7.95; 7.65; 7.30; 7.20; 6.80; and 6.00 microns, when examined by infrared light in accordance with the method used for determining infrared absorption as described in an article by W. H. Avery. entitled Infrared spectrometer for industrial use, which appears in the J. Optical Soc. Am. 31, 633-638 In a reaction vessel in which the air has been displaced with nitrogen, 13.4 parts of cuprous chloride are dissolved in 203 parts of 8.7% aqueous ammonia solution. Any blue color from cupric salts present in the cuprous chloride is removed by slowly adding a small quantity of a reducing agent such as sodium hydrosulfite. 20.8 parts of the distilled mercaptan having a boiling range of 1l4.5-1l4.6 C. derived from alphapinene as above described, dissolved in 36 parts of ether (or low boiling naphtha) are added to the solution and the mixture agitated for two hours under a nitrogen atmosphere. A reflux condenser or external cooling is preferably employed as the heat of reaction is often sufficient to vaporize a portion of the ether. The ether layer (upper) is decanted from the aqueous layer (lower), and filtered to remove traces of insoluble material. This ether fraction is then evaporated under vacuum at room temperature, giving a quantitative yield of the copper mercaptide derived from alpha-pinene which is a bright yellow solid. The yield is based upon the mercaptan employed. The copper mercaptide derived from the alpha-pinene as thus produced softens at 116 C. and melts at 122 C., it has a sulfur content of 13.75% and a copper content of 26.42%. The product is soluble in hydrocarbon solvents such as benzene, hexane, parafiin oil and in ether, alcohol, dioxane, etc.

Example 2 Where beta-pinene having a boiling range of 163.0 C. to l72.6 C. with 80% distilling between 164.0 C. and 167.0 C., a specific gravity of 0.8714 and a refractive index of Nzo 1.4750, is substituted e 10 hours.

in Example 1 for alpha-pinene a meroaptan is obtained having a boiling range of Ill-113 C., a refractive index of Nzs 1.5044 and a sulfur content of 18.85%. The copper mercaptide derived from the beta-pinene by the process above given melts at 81 C. to 83 C. and contains 13.86% sulfur and 23.94% copper.

Example 3 1088 parts of alpha-pinene (of the quality defined above), 246 parts of sulfur and 55 parts nickel catalyst are charged into an autoclave and heated for 8 hours at 150 C. Then hydrogen pressure at 500 pounds is placed on the autoclave and the reaction mass is reduced until no further pressure drops occurred. This requires approximately 10 hours. The reaction mass is cooled and discharged. The reaction mass is heated to 70 C. under vacuum with nitrogen passing over it until all the hydrogen sulfide is removed.

75 parts of 36% sodium bisulfite, 60 parts of 30% sodium hydroxide, 33 parts of sodium chloride and 400 parts of water are stirred until complete solution occurred. This solution is then heated to 70-80 C. and to it is added slowly parts of CuSO4-5H2O. The water is decanted after allowing the cuprous chloride to settle. It is washed twice with water containing a little sodium sulfite, then 100 parts by volume of aqueous ammonia are added and the mass is allowed to stand until complete solution occurs. 150 parts of water containing a little sodium hydrosulfite is added. To this solution is then added 50 parts of the crude mercaptan from pinene as prepared in the preceding paragraph and the mass is stirred for one hour at room temperature. The reaction mass is then allowed to settle and the thick lower liquid drawn off. This is stirred with acetone and the acetone decanted. Thi operation is repeated until the pasty reaction mass becomes solid, and finally turns to a thick powder. It is then filtered, washed with acetone and dried. The copper compound of the mercaptan so obtained is substantially identical with the product of Example 1 for the impurities have been removed by the acetone wash.

Example 4 1370 parts of alpha-pinene of the quality above described and 320 parts of sulfur are heated to 150 C. over a period of two hours then held at that temperature for 8 hours. The reaction mass is cooled and 68 parts of nickel catalyst are added and the mass is again heated to 150 C. under hydrogen pressure of 500 pounds. The pressure is allowed to drop to 400 pounds and then brought up to 500 pounds until no more pressure drops occurred. This takes approximately The product is filtered from the catalyst, and distilled under a 3 mm. vacuum without collecting any foreruns. The total distillate at 3 mm. pressure up to 98 C. is collected.

500 parts of CuSO4-5H2O are dissolved in 1600 parts of water and parts of salt are added. This copper salt is reduced by adding 350 parts of a 36% solution of sodium bisulfite containing 276 parts of 30% sodium hydrosulfite. If complete reduction is not effected, 70 parts more of 36% sodium bisulfite and 56 parts of 30% sodium hydrosulfite and 13 parts of salt are added. The aqueous layer is decanted and the cuprous chloride washed and then dissolved in 400 parts of ammonia and 200 parts of water containing a little sodium hydrosulfite. To this solution is added a solution of 290 parts of distilled mercaptan derived from pinene as prepared in the preceding paragraph dissolved in 200 parts of benzene. This reaction mass is stirred for 3.5 hours at room temperature, the copper solution decanted and the organic solvent layer washed five times with water. The benzene layer is separated and the benzene evaporated off under vacuum. The residual materialis poured into acetone in a fine stream with good agitation. The acetone is decanted and the material is again treated with freshacetone. This operation is repeated until the material has hardened and is easy to break up into small pieces. The mass is then filtered and dried under vacuum. The product is substantially identical with the product of Example 1.

It is of course understood that when the starting material contains a difierent ratio of isomers or impurities which form the copper mercaptides the resulting copper compounds may differ in their melting range from that given in the specific examples.

As illustrated in the above examples the copper compounds of the mercaptans derived from pinenes may be produced from the-isolated mercaptans or they may be produced from the crude mercaptans for in the copperization step any unreacted material or impurities which do not form the copper salts are eliminated by the acetone extraction or by the use of similar solvents which do not dissolve the copper mercaptide The acetone wash may of course he omitted if the mercaptan which is employed is rel-- atively pure or the acetone may be substituted by other solvents.

The ether employed as the solvent for the mercaptan in the preparation of the copper compound may be omitted or it may be substituted by other organic solvents such as benzene, ligroin, kerosene, petroleum ether or lubricating oils. The use of the solvent in this reaction is preferred for it facilitates Working up of the final product.

This invention contemplates the preparation of new copper mercaptides derived from pinenes,

irrespective of the process employed for the preparation of the mercaptan derived from the pinene and it will be obvious that the mercaptan derived from the pinene may be produced by other processes than those mentioned above such as by the use of hydrogen sulfide or by replacing a halogen in the pinene molecule by the SH group.

I claim:

1. The copper compound of a mercaptan derived from a pinene which compound is obtained by reacting a mercaptan derived from the pinene by the introduction of an -SH group into the pinene with a cuprous salt in the presence of a reducing agent capable of maintaining the copper salt in the cuprous state.

2. The copper compound of a mercaptan derived from a pinene which compound is obtained by heating the pinene with sulfur at temperatures sufiicient to cause the formation of a pinene-sulfur complex, reducing this complex by reacting it with hydrogen under pressure in the presence of a hydrogenation catalyst to form the mercaptan and reacting the resulting mercaptan derived from the pinene with a copper salt under conditions whereby the copper salt is maintained in the cuprous state. i

3. The copper compound of a mercaptan derived from alpha-pinene which compound is obtained by heating the pinene with sulfur at temperatures sufiicient to cause the formation of a pinene-sulfur complex, reducing this complex by reacting it with hydrogen under pressure in the presence of a hydrogenation catalyst to form the mercaptan. and reacting the resulting mercaptan derived from the pinene with a copper salt under conditions whereby the copper salt is maintained in the cuprous state.

4. The copper compound of a mercaptan derived from beta-pinene which compound is obtained by heating the pinene with sulfur at temperatures sufficient to cause the formation of a pinene-sulfur complex. reducing this complex by reacting it with hydrogen under pressure in the presence of a hydrogenation catalyst to form the mercapta'h and reacting the resulting mercaptan derived. from the pinene with a copper salt under conditions whereby the copper salt is maintained in the cuprous state.

ARTHUR L. FOX. 

